The present invention can be used with various types of bladders (or cells) used in inflatable cushions, mattresses or pads. In many cases these cushions, mattresses and pads are therapeutic and used by hospitals, businesses, and residences.
There are various types of cushions, mattresses or pads (collectively referred to as mattresses). Some of these variations are disclosed in commonly assigned U.S. Pat. No. 5,901,393 (Pepe et al.; title: Alternating Pressure Support Pad), and U.S. Pat. No. 6,079,070 (Flick; title: Disposable Inflatable Inclinable Cushion), which are hereby incorporated by reference. Obviously, these patents fail to disclose every type of inflatable mattresses but it does provide a representative sample.
In synopsis, every inflatable mattress has at least one bladder. That bladder can be made of polymeric materials having a top surface capable of receiving an object, a bottom surface that is opposite the top surface, and at least one side positioned between the top and bottom surfaces. In addition, every inflatable bladder is capable of receiving through an inlet a fluid, normally air or an aqueous solution, from a fluid source, normally a pump. From this fundamental understanding of inflatable bladders, the variations of bladders become evident. For example, some bladders (1) have the inlet of the fluid removed to become a self-contained device and (2) retain an inlet to receive fluid to become a dynamic device.
In the latter embodiment, the fluid exits the bladder through at least one outlet. In one version, the fluid exits the outlet through a conduit to return to the fluid source. In other versions the fluid exits the outlet through a conduit to a receiving unit, distinct from the fluid source. Another version has the surface of the bladder having a plurality of apertures designed to release at least a portion of the fluid toward the object lying on the inflatable bladder. Some bladders may have a CPR dump system to release the fluid expeditiously from the bladder.
Obviously, there may be alternative embodiments to these generic descriptions of bladders. In addition, the bladders may have alterations to (1) generate desired fluid flow patterns, (2) obtain desired mattress firmness and (3) allow the bladder adaptability for the mattress system. To obtain such results and others like it, the bladders have predetermined button welds, welds, and slits along welds. In addition, many of these alternative embodiments are embodied in numerous patent applications and patents, and product configurations.
As previously stated, numerous, if not all, inflatable bladders are constructed of some type of film material. The film material can be, for example, vinyl, polyethylene, or combinations thereof. When such film materials are used, the applicants have determined that the ability of the bladder to support loads for extended periods of time is greatly affected by creep of the material.
Creep occurs when an object, like a human, is placed on the mattress and displaces the air, at least immediately below the object, to the extremities of the bladder. Over time, creeping of the mattresses allows the object to bottom out on the inflatable mattress. Such results are undesirable and need to be minimized.